72820981 has 2 divisors, whose sum is σ = 72820982. Its totient is φ = 72820980.

The previous prime is 72820949. The next prime is 72820987. The reversal of 72820981 is 18902827.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71402500 + 1418481 = 8450^2 + 1191^2 .

It is a cyclic number.

It is not a de Polignac number, because 72820981 - 2⁵ = 72820949 is a prime.

It is a super-2 number, since 2×72820981² = 10605790547604722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 72820981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72820987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36410490 + 36410491.

It is an arithmetic number, because the mean of its divisors is an integer number (36410491).

Almost surely, 2^72820981 is an apocalyptic number.

It is an amenable number.

72820981 is a deficient number, since it is larger than the sum of its proper divisors (1).

72820981 is an equidigital number, since it uses as much as digits as its factorization.

72820981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 72820981 is about 8533.5210200714. The cubic root of 72820981 is about 417.5920047750.

The spelling of 72820981 in words is "seventy-two million, eight hundred twenty thousand, nine hundred eighty-one".